A conventional hinge device disclosed in patent literature 1 supports the other member in a manner rotatable to one member. In a ceiling-mounted monitor device, for example, the one member is a base member mounted on the ceiling of a vehicle and the other member is a monitor panel. The monitor panel is rotatably supported to the base member by the hinge device.
The hinge device disclosed in patent literature 1 includes a bracket, a shaft, a brake member, a flat spring member, and a torsion spring.
The bracket is a member fixed to the base member. The shaft is a rotating shaft fixed to the monitor panel. The brake member is a flat member fixed to the shaft, and rotates together with the shaft in an urged state toward the bracket. The flat spring member is a member fixed to the shaft and urges the brake member toward the bracket. The torsion spring is wound around the shaft and applies a rotational force to the shaft. The torsion spring applies an initial torque to the shaft when the monitor panel is rotated.
A protrusion is formed on a surface of the brake member on the side facing the bracket. On a surface of the bracket facing the brake member, a tapered groove or a depressed groove whose opening width is gradually increased, in which the protrusion of the brake member moves in contact with them, and a hole that receives the protrusion of the brake member are formed.
The brake member, the bracket, the flat spring member, and a washer are placed on an end segment of the shaft in this order, and the end segment is swaged to retain these components.
When the monitor panel is unlocked from a stored position in the base member, the monitor panel pops out from the base member caused by the initial torque of the torsion spring.
While the protrusion of the brake member is moving through the tapered groove or the depressed groove of the bracket, the torque gradually decreases because the urging of the protrusion is gradually damped by the tapered groove or the depressed groove.
High torque is generated when the protrusion of the brake member moves out of the tapered groove or depressed groove of the bracket and onto the side surface of the bracket, and a maximum torque is generated when the protrusion of the brake member is received by the hole in the bracket. This position is the viewing position of the monitor panel.
In the above hinge device, the end segment of the shaft has a noncircular cross-section, and each of the through-holes formed in the brake member, the flat spring member, and the washer, respectively, also has the same shape as the cross-section of the end segment. This causes the brake member, the flat spring member, and the washer to rotate together with the shaft.
The opening area of each of these through-holes is formed to be larger than the cross-sectional area of the end segment of the shaft so that the end segment can be certainly inserted to the through-holes. That is, a slight gap is provided between the end segment of the shaft and the through-holes.